Multiphase extractor with a wash chamber

ABSTRACT

Multi phase extractor, comprising an extraction chamber, a washing chamber and a re-extraction chamber, said chambers each having inlets adapted to disperse and discharge a phase therein, and connecting channels adapted to convey a continuous phase from said extraction chamber to said washing chamber, from said washing chamber to said re-extraction chamber from said re-extraction chamber to said extraction chamber, and each of said chambers having drains for removing the phase discharged into it by said inlets.

The invention is based on a multiphase extractor having an extractionchamber and a re-extraction chamber which are connected in their upperand lower parts by connecting channels and have distribution devices andconnectors for the supply and discharge of a donor phase and an acceptorphase.

A multiphase extractor of this type can be used in the chemical,hydrometallurgical, microbiological and other sectors of industry forthe separation, extraction, concentration and purification ofsubstances.

BACKGROUND OF THE INVENTION

From the technical point of view and regarding the achievable effect,the closest of the known apparatuses is the three-phase extractordescribed in Russian Patent Application 94-015776/26, which consists ofan extraction chamber and a re-extraction chamber which are filled withthe continuous phase (liquid membrane). The chambers have devices fordispersing the respective phase and are connected to one another viaoverflows for the circulation of the continuous phase. The overflows arein the form of connecting channels or pipes which connect the upper andlower parts of the chambers to one another. The extractor is providedwith connectors for the supply and discharge of the first and seconddisperse phases. The first phase to be dispersed, which is the startingsolution, or donor phase, and contains the substance to be removed, andthe second phase to be dispersed, the acceptor phase, are each dispersedin the corresponding chamber in the form of droplets by means of adispersion or distribution device. These droplets move through thecontinuous phase as a stream of droplets. Owing to the densitydifference in the dispersions in the first and second chambers,circulation of the continuous phase takes place through the upper andlower overflows, resulting in transfer of the extracted substance fromone chamber into the other and from the donor phase into the acceptorphase. Thus, extraction with the continuous phase as extractant takesplace in the first chamber, and re-extraction of the removed substancewith the acceptor phase as re-extractant takes place in the secondchamber.

SUMMARY OF THE INVENTION

The invention has the object of modifying the multiphase extractor toenable further possible applications in which extraction andre-extraction processes can be coupled with washing processes in asingle apparatus. In particular, washing of the extractant should alsobe enabled here.

This object is achieved in accordance with the invention in themultiphase extractor described at the outset through the extractionchamber and re-extraction chamber being connected to one another via anintermediate washing chamber.

According to a preferred embodiment of the invention, the extraction,re-extraction and washing chambers are equipped with separation zones.

According to a preferred embodiment, the upper part of the extractionchamber is connected directly to the upper part of the re-extractionchamber.

Alternatively, the upper part of the extraction chamber can be connecteddirectly to the lower part of the re-extraction chamber.

A further alternative consists in that the lower part of the extractionchamber is connected directly to the lower part of the re-extractionchamber.

A further refinement of the invention is characterized in that theextraction chamber and the re-extraction chamber together with thewashing chamber form a single separating stage, and a series of suchstages are connected in series in the form of a cascade.

The incorporation of washing chambers between the extraction andre-extraction chambers allows coupled extraction, washing andre-extraction processes to be carried out in one and the same apparatus.

The different types of connection between the extraction andre-extraction chambers provide the prerequisite for achieving differenttechnological variants of the separation process (co-current orcountercurrent flow of the extractant with the donor, washing andacceptor phases).

The connection of a plurality of separation stages, each consisting ofan extraction chamber, a washing chamber and a re-extraction chamber, inseries in a cascade-like arrangement allows multistage mass transferprocesses to be carried out in the multiphase extractor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-7 show diagrammatically various embodiments of the multiphaseextractor according to the invention for carrying out coupledextraction, washing and re-extraction processes. In the figures:

FIGS. 1-6 show various embodiments of single-stage extractors, and

FIG. 7 shows a multistage multiphase extractor.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1-6, the multiphase extractor consists basically of anextraction chamber 1, a re-extraction chamber 2 and a washing chamber 3,which is arranged between the two chambers 1 and 2. In FIGS. 1 and 2,the upper parts and in FIGS. 5 and 6, the lower parts of the extractionchamber 1 and re-extraction chamber 2 are connected directly to oneanother via the connecting pipe 5, which runs around the outside of thewashing chamber 3. Separation zones 6 in the form of an increase incross section of the chambers 1, 2, 3 are provided at the inlet openingsof the connecting pipes 5. The separation zones, which act as depositionchambers, prevent droplets being dragged from one chamber into the otherby the circulating stream of continuous phase.

Chamber 1 is supplied with a donor phase via connector 8, chamber 2 issupplied with an acceptor phase via connector 10 and chamber 3 issupplied with a washing liquid (washing phase) via connector 9. In orderto disperse the phases, distribution devices 4 are installed at the endsof the connectors. The washing chamber 3 likewise has a separation zone6. The lower part of the extraction chamber 1 can be connected to theupper part (FIG. 1) or lower part (FIG. 2) of the washing chamber 3. Inthe extractor in FIG. 1, the extractant flows in countercurrent to theacceptor phase and in co-current with the donor and washing phases. Inthe extractor in FIG. 2, by contrast, the extractant flows incountercurrent to the washing phase and in co-current with the acceptorand donor phases.

FIGS. 3 and 4 show embodiments of the multiphase extractor in which theupper part of the first chamber 1 (extraction chamber) is connecteddirectly to the lower part of the second chamber 2 (re-extractionchamber), the connecting pipe 5 again running behind the washing chamber3.

The starting solution (donor phase) is, as in the embodiments describedabove, fed into the extraction chamber 1 via connector 8. The substanceto be extracted is extracted by the continuous phase (extractant). Theextractor phase (i.e. the continuous phase loaded with the extractedsubstance) passes through the connecting pipe 5 into the washing chamber3, where it is washed by the washing medium fed in via connector 9. Thewashed extractor phase passes from the washing chamber 3 into there-extraction chamber 2, where the re-extraction by the acceptor phasetakes place. During transfer from one chamber into the other, thecontinuous phase flows through the separation zones 6 and 7 in chambers1, 2 and 3, causing any droplets of donor, washing or acceptor phasewhich have been dragged along by the flow to be deposited. The donor,washing and acceptor phases are discharged from chambers 1, 2 and 3 viaconnectors 11, 12 and 13.

In the multistage extractor shown in FIG. 7, the extraction, washing andre-extraction processes are repeated in each stage. Depending on howchambers 1, 2 and 3 are connected to one another, different flowvariants of the material separation process can be achieved (co-currentor countercurrent).

We claim:
 1. Multiphase extractor comprising an extraction chamber, are-extraction chamber and an intermediate washing chamber, each of saidchambers having a bottom section and a top section, and wherein saidextraction chamber has an inlet for the supply of a donor phase, saidinlet being adapted to disperse a donor phase and discharge it as adispersion into said extraction chamber, a drain at the bottom sectionof the extraction chamber, a first connecting channel which connectssaid extraction chamber to said washing chamber and a second connectingchannel which connects said extraction chamber to said re-extractionchamber, said first and second connecting channels being connected tosaid extraction chamber at a level which is above the level of saiddrain at the bottom section of said extraction chamber, saidintermediate washing chamber has an inlet for the supply of a washingphase, said inlet being adapted to disperse a washing phase anddischarge it into said washing chamber, a drain at the bottom section ofthe washing chamber, a third connecting channel which connects saidwashing chamber to said re-extraction chamber, said third connectingchannel being connected to said washing channel at a level which isabove the level of said drain at the bottom section of the washingchamber said re-extraction chamber has an inlet for the supply of anacceptor phase, said inlet being adapted to disperse an acceptor phaseand discharge it as a dispersion into said re-extraction chamber, adrain at the bottom section of the re-extraction chamber and whereinsaid second connecting channel which connects said re-extraction chamberand said extraction channel is connected to said re-extraction chamberat a level which is above the level of said drain at the bottom sectionof said re-extraction chamber.
 2. Multiphase extractor according toclaim 1, wherein said extraction chamber comprises a phase separationzone having an upper section and a lower section, said drain at thebottom of said extraction chamber is connected to the bottom section ofsaid separation zone, and said first connecting channel is connected tothe upper section of said separation zone.
 3. Apparatus according toclaim 1, wherein said second connecting channel connects the top sectionof the re-extraction chamber to the top section of the extractionchamber.
 4. Apparatus according to claim 1, wherein said secondconnecting channel connects the bottom section of the re-extractionchamber to the top section of the extraction chamber.
 5. Apparatusaccording to claim 1, wherein said second connecting channel connectsthe bottom section of the re-extraction chamber to the bottom section ofthe extraction chamber.
 6. Apparatus according to claim 1, wherein theextraction chamber and the re-extraction chamber together with thewashing chamber form a single separation stage, and a number of saidseparation stages are connected in series.
 7. Multiphase extractoraccording to claim 1, wherein said washing chamber comprises a phaseseparation zone in the bottom section thereof, said phase separationzone having an upper section and a lower section, said drain at thebottom of said washing chamber is connected to the bottom section ofsaid phase separation zone, and said third connecting channel isconnected to the upper section of said phase separation zone. 8.Multiphase extractor according to claim 1, wherein said re-extractionchamber comprises a phase separation zone in the bottom section thereofsaid phase separation zone having an upper section and a lower section,said drain at the bottom of said re-extraction chamber is connected tothe bottom section of said phase separation zone, and said secondconnecting channel is connected to the upper section of said phaseseparation zone.
 9. Multiphase extractor of claim 1, wherein one or moreof said extraction chamber, said washing chamber and said re-extractionchamber has a separation zone in the top section thereof.